In a medication delivery device, a piston within a cartridge that contains medication may be displaced with respect to the cartridge in the distal direction by a piston rod which moves in the distal direction with respect to the cartridge. Thereby, a dose of medication can be expelled from the cartridge. A medication delivery device is described in US 2007/0123829 A1, for example.
It is often desirable that the actually delivered dose of medication matches the dose which was previously set for injection by a user or which the device was designed to deliver as close as possible, i.e. dose accuracy should be good.
It is an object to provide for a drive mechanism that facilitates provision of an improved medication delivery device, for example a device with good dose accuracy. Furthermore, an improved medication delivery device should be provided for.
This object may be achieved by a drive mechanism according to the independent claim. Further features, advantages and expediencies are subject matter of the dependent claims.